Microstrip-Slot Coupler Design-Part II: Practical Design Aspects

Practical aspects of designing microstrip-slot couplers on an Al ₂O ₃ ceramic substrate (epsilon _r = 9.8) are treated in supplementation of the theoretical analysis of the coupler presented in Part I. Comparison with implemented couplers yields rules for specification of the reference planes at the ends of the coupling section, for the appropriate choice of definition for the slot-line characteristic impedance. Design data of the standard versions of the microstrip transmission line, the slot line are shown to be adequate for the microstrip-slot coupler. Computed S -parameter curves plotted for various 3-dB couplers yield information on realizable transmission characteristics.